This contract conducts confirmatory cell-based in vitro testing of experimental therapeutic agents for the prevention and treatment of infections caused by human immunodeficiency virus (HIV). Compounds are evaluated as single agents or in combination with other AIDS therapies for antiviral efficacy and cytotoxicity. Evaluations can be conducted against a wide variety of virus isolates in established cell lines, peripheral blood mononuclear cells, or macrophages. This contract is part of a portfolio of contracts administered by the National Institute of Allergy and Infectious Diseases to facilitate the development of promising therapeutic approaches for the prevention and treatment of infections caused by HIV.